A model for APC/C-Cdh1-mediated anaphase progression. (A) APC/C-Cdc20-mediated anaphase progression in normal cell cycle. (B) APC/C-Cdh1-mediated anaphase and telophase progression during mitotic slippage. When proper kinetochore-microtubule attachments are not established, the SAC inhibits APC/C-Cdc20-mediated anaphase onset. However, loss (bub2Δ) or impairment of Bub2 function causes APC/C-Cdh1 triggered anaphase progression and telophase onset (mitotic exit). For details, see the text. (C) Schematic representation of securin proteins in S. cerevisiae (Pds1), Schizosaccharomyces pombe (Cut2), Drosophila (PIM) and Human (hPTTG). Blue and red lines indicate D- and KEN boxes.